[PATCH] usb: typec: tcpm: recover after failure to start the frs ams

[Amit Sunil Dhamne via B4 Relay <devnull+amitsd.google.com@kernel.org>]

From: Amit Sunil Dhamne <amitsd@google.com>

Reset the port if the tcpm fails to start the FAST_ROLE_SWAP AMS by
initiating error recovery on it.

This helps in cases where some cables (incorrectly) signal an FRS to
an FRS capable port during disconnection. The TCPC autonomously starts
sourcing VBUS on detecting the FRS signal. However, the VBUS sourcing is
left on when the FAST_ROLE_SWAP AMS fails to start (as tcpm_sink_tx_ok
is 0 as CC is open due to the cable disconnect). This is because the
code sets the state to INVALID_STATE without resetting the port state.

Log snippet before changes:
[  101.401960] AMS FAST_ROLE_SWAP start
[  101.401971] Sink TX No Go
[  101.401982] sourcing vbus
[  101.401987] VBUS on
[  101.402159] VBUS on
[  109.257809] CC1: 0 -> 0, CC2: 5 -> 0 [state SNK_READY, polarity 1, disconnected]
[  111.267442] VBUS on

After changes:
[   70.541211] AMS FAST_ROLE_SWAP start
[   70.541220] Sink TX No Go
[   70.541228] state change SNK_READY -> ERROR_RECOVERY [rev3 NONE_AMS]
[   70.541362] VBUS on
[   70.541365] sourcing vbus
[   70.541367] VBUS on
[   70.541374] state change ERROR_RECOVERY -> PORT_RESET [rev3 NONE_AMS]
[   70.541410] disable vbus discharge ret:0
[   70.543028] Setting usb_comm capable false
[   70.544009] Setting voltage/current limit 0 mV 0 mA
[   70.544034] polarity 0
[   70.544239] Requesting mux state 0, usb-role 0, orientation 0
[   70.555550] cc:=0
[   70.555595] pending state change PORT_RESET -> PORT_RESET_WAIT_OFF @ 100 ms [rev3 NONE_AMS]
[   70.555697] VBUS off
[   70.555702] VBUS VSAFE0V
[   70.555762] CC1: 5 -> 0, CC2: 0 -> 0 [state PORT_RESET, polarity 0, disconnected]
[   70.587794] VBUS off
[   70.587799] VBUS VSAFE0V
[   70.655672] state change PORT_RESET -> PORT_RESET_WAIT_OFF [delayed 100 ms]
[   70.655682] state change PORT_RESET_WAIT_OFF -> SNK_UNATTACHED [rev3 NONE_AMS]
[   70.655686] Start toggling
[   70.656274] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]

Fixes: 0908c5aca31e ("usb: typec: tcpm: AMS and Collision Avoidance")
Cc: stable@vger.kernel.org
Signed-off-by: Amit Sunil Dhamne <amitsd@google.com>
Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index a8cd1959c426..c1045d850897 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -7113,7 +7113,7 @@ static void tcpm_pd_event_handler(struct kthread_work *work)
 				port->upcoming_state = FR_SWAP_SEND;
 				ret = tcpm_ams_start(port, FAST_ROLE_SWAP);
 				if (ret == -EAGAIN)
-					port->upcoming_state = INVALID_STATE;
+					tcpm_set_state(port, ERROR_RECOVERY, 0);
 			} else {
 				tcpm_log(port, "Discarding FRS_SIGNAL! Not in sink ready");
 			}

---
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
change-id: 20260903-frs-error-handling-253b87a09fa2

Best regards,
-- 
Amit Sunil Dhamne <amitsd@google.com>